290 DISCOVERY REPORTS 



The dorsal organ is high and abrupt. The frontal plate is square, its lateral margins 

 nearly parallel, its corners squarely rounded ; the anterior margin is weakly emarginate 

 with a small projection, the rostral spine, arising from its centre ; the anterior and the 

 lateral margins are strongly denticulate. The lateral margins of the carapace remain 

 denticulate for a part of their length, from some way posterior to the antero-lateral 

 spines to some way anterior to the lateral denticles. The posterior projection of the 

 carapace is very strong and wide-based in both specimens ; in one it reaches to the end of 

 the second, in the other to near the end of the third, abdominal somite. 



The antennular spine is longer, the flagella considerably longer, than the sum of the 

 second and third segments of the peduncle. The flagella are not yet distinctly seg- 

 mented. 



The thoracic limbs of the larger specimen are as follows : 



First limb. Endopod short, of same length as exopod. 



Second limb. Endopod of five segments and kneed. Gill of two unequal branches. 



Third limb. Endopod shorter than second and feebly kneed. Gill of two unequal 

 branches. 



Fourth limb. Endopod much shorter than third, of five segments but not kneed. 

 Gill of two unequal branches. 



Fifth limb. Very short, bifurcating, non-setose, with a single gill bud. 



Sixth limb. A small undifferentiated bud. 



Seventh limb. A small gill bud of two unequal branches. 



Eighth limb. A small undifferentiated bud. 



The hinder lower edges of the pleura of the abdominal somites are very finely 

 denticulate. The spine of the third segment is about half the length of the fourth. The 

 distal end of the telson is narrower than in the previous stage. The middlemost of the 

 postero-lateral spines is still the longest, the innermost is greatly thickened at the base. 



Furcilia, stage IV (Fig. 39^) 

 Description based on the examination of five specimens, 6-5-6-9 mm. long. 



In this stage the antennal endopod is unsegmented and there are five pairs of setose 

 pleopods. 



The dorsal organ is high and abrupt. The frontal plate is wide and square with its 

 corners rounded and its margins beset with denticles ; the centre of its anterior margin 

 is produced into a strong rostral spine with a wide base which reaches as far as halfway 

 along, or nearly to the end of, the second segment of the antennular peduncle. The same 

 portions of the lateral margins of the carapace are denticulate as in the previous stage 

 (Fig. 39^). The posterior projection of the carapace is strong and reaches as far as the 

 end of the second, or halfway down the third, abdominal somite. 



The antennular spine is as long as or longer than the sum of the second and third 

 segments of the peduncle. The flagella are long and segmented. 



